Thiol-C9-PEG5 is widely used in bioconjugation and surface modification due to its unique properties. The thiol group allows for strong covalent bonding with gold, silver, and other metals, making it ideal for creating self-assembled monolayers (SAMs) on surfaces. This is particularly useful in biosensors, where it enhances the immobilization of biomolecules like proteins or DNA, improving sensitivity and specificity.

In drug delivery systems, Thiol-C9-PEG5 is employed to functionalize nanoparticles or liposomes. The PEG (polyethylene glycol) segment provides steric stabilization, reducing immune recognition and prolonging circulation time in the body. This makes it valuable for targeted drug delivery and therapeutic applications.

Additionally, it is utilized in the development of biofunctional coatings for medical devices. The thiol group ensures robust attachment to surfaces, while the PEG segment imparts biocompatibility, reducing protein adsorption and preventing unwanted cellular interactions. This is critical for improving the performance and safety of implants and diagnostic tools.